As is known in the art, chewing gum compositions include a number of ingredients, some of which are subject to deterioration through oxidation during storage. Mint oils are important ingredients of chewing gum which require stabilization, both before and after the mint oils are incorporated into the chewing gum. The term "mint oil" as used herein includes, but is not limited to, peppermint oil, spearmint oil, corn mint oil and Scotch spearmint oil. The use of peppermint oil in chewing gum, enhanced with a minor amount of spearmint oil, is discussed in U.S. Pat. No. 4,948,595 issued to Patel et al.
Several synthetic antioxidants are in widespread use for stabilizing mint oil and mint flavored chewing gum compositions. Among the most notable of these synthetic antioxidants are Butylated Hydroxy-anisole (BHA), Butylated Hydroxytoluene (BHT) and tertiary butyl hydroquinone (TBHQ). While BHA, BHT and TBHQ are effective in preventing and reducing oxidation of mint oil and mint flavored chewing gum compositions, there is nevertheless a demand for antioxidant systems which can be derived entirely from natural sources.
U.S. Pat. No. 5,139,796, issued to Barkalow et al., discloses that certain mixtures of tocopherol homologs, in certain ratios, exhibit improved antioxidant properties when used in chewing gum. Tocopherols are naturally occurring compounds which are FDA approved and which have been shown to be safe in animal testing. Expressed as percentage ranges of active ingredients (i.e. weight percentages based on total tocopherols), the preferred homolog ranges are 7-15% alpha tocopherol, 45-70% gamma tocopherol, and 20-35% delta tocopherol. Tenox GT-2 is a commercially available tocopherol blend whose homolog concentrations fall within these ranges. Tenox GT-2 contains about 10.2% alpha tocopherol, 61.6% gamma tocopherol, and 28.2% delta tocopherol (based on total tocopherols) is a soybean oil diluent (70% tocopherol mixture, 30% soybean oil). Tenox GT-2 is preferably employed in an amount sufficient to give an active tocopherol level of about 0.05-0.50% based on the weight of the mint oil.
The chewing gum industry is continuing to investigate other natural antioxidants which can stabilize mint oil, especially peppermint oil, and mint flavored chewing gums, without employing synthetic antioxidants.